CSI Malawi: Using forensic science to "interrogate" mosquitoes

MSU's Edward "Ned" Walker has been involved in research work in the fight against malaria in Malawi for seven years.

Fifteen years ago, Edward “Ned” Walker, a Michigan State University medical entomologist, spearheaded the use of insecticide-treated bed nets in the fight against malaria in Africa. Now, a seven-year, $8 million NIH-sponsored grant will enable Walker and his team to use a new, creative approach—forensic science.

“In the very poor, rural areas of Malawi, people’s houses aren’t very sophisticated; school-age children don’t have assigned sleeping spaces in their homes,” explained Walker, who is also an MSU AgBioResearch scientist and holds a joint appointment in the MSU Department of Entomology. “They roll a mat out on the floor where there’s some space and lie down and sleep. The mothers and babies most often sleep protected by a bed net. This changes the exposure group and the structure of pathology changes.”

In fact, the researchers have discovered that the malaria epidemiology spectrum has recently shifted—from children under the age of five, to school-age children.

“That has a lot of implications,” said Walker said. “We’re trying to better understand why that happened, and what we can do about it. Maybe the answer is school-based intervention systems.

“What we’re interested in is the transmission driver,” he added. “Mosquitoes don’t bite randomly. They bite some people more than others.”

Walker and his team collaborated with David Foran, director of MSU's Forensic Science Program, School of Criminal Justice, in the College of Social Science, to develop tools to “interrogate” mosquitoes.

“After a blood meal, mosquitoes rest on the walls inside the homes. We collect the mosquitoes and can determine not only if the mosquito has bitten an animal or a human—but can actually pinpoint, using forensic analysis, which individual inside the home the insect has drawn blood from,” Walker said. “We can genotype them. And now, we’re developing a tool so we can determine what malaria parasites are also in that blood.”

Walker added that Malawi was one of three countries recently chosen by the World Health Organization (WHO) as a large-scale test site for a new malaria vaccine. This could present an opportunity for the MSU scientists to weave in the vaccine study with their own research.

In August, all of the NIH grant awardees will meet in Washington, D.C., for the official launch of the project. The goal is that all nine centers will focus on the same problems, identify the common questions, and discuss the best way to attack the issue.

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